dramatic kidnapping on the high seas. Two americans taken hostage, singled out by pirates attacking the ship. Abc's brian ross has the latest for us. Reporter: U.S. Officials believe the two americans have been taken in the hard-to-reach mangrove swamps of nigeria. Safe haven for pirate groups that made a fortune kidnapping american and foreign oil workers in the region. They're for sophisticated than they operate. They're better funded. They don't take ships in west africa. They're really going after ransoms. Reporter: The americans were taken off the oil rig supply ship, "the sea retriever," in broad daylight. The pirates sorted the crew by nationalities and took captive only the two americans. You take americans, you get a good price. But at the same time, you bring a lot of heat on you, too. Reporter: The u.S. Says there is no current plan for a military rescue. Unlike the dramatic case portrayed in the current hit movie "captain phillips," when U.S. NAVY S.E.A.L.s WERE BROUGHT In to rescue the captain from somali pirates. The actual captain, richard phillips, told pierre thomas, that pirates are now just part of the job for a sea captain. If you don't want to deal with piracy, you need to get another job. Reporter: In fact, piracy on the high seas seems to be a booming criminal business. Especially in the area off nigeria, through which some 30% of the u.S. Oil supply moves. It's a very attractive place to operate in terms of a ransom that you can get and the damage you can do to the industry. So, that's a big problem. Reporter: This morning, while nigerian security forces search for the two men, fbi agents have been assigned overseas and here in the u.S., To help the families of the two sailors, as they wait for the pirates to make contact and to learn what it will take to get their loved ones back. Robin? We hope that will be soon. Brian, thank you. Thank you, guys.

This transcript has been automatically generated and may not be 100% accurate.

Pirates Seize 2 Americans Off Ship Near Nigeria

The captain and an engineer onboard an oil supply vessel were taken ashore to Nigeria.

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